Physical origin of the high output conductance in In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP HEMTs

The underlying device physics of the In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP HEMT drain I-V characteristic are discussed. A model of premature current saturation (PCS) is proposed to explain the improvements in the output conductance achieved by the low conductance drain (LCD) HEMT. Using this model, it is shown that the high output conductance observed in conventional highly doped cap In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP HEMTs is caused by a high transverse channel electric field near the drain, which results in hot electron induced two-dimensional electron gas (2DEG) carrier deconfinement (i.e., real-space transfer), causing the drain current to saturate prematurely (i.e., incomplete saturation).<
>